1. Field of the Invention
The present invention is related to a personal navigation device and related navigating method, and more particularly, to a personal navigation device which provides portable electronic map and related navigating method.
2. Description of the Prior Art
GPS (Global Positioning System) is a space-based global navigation satellite system which provides reliable location and time information in all weather, at all times, and almost anywhere on or near the Earth. GPS-based personal navigation devices are well known and widely employed as in-car navigation devices. Common functions of a personal navigation device include providing a map database for generating navigation instructions which are then shown on a display of the personal navigation device. In order to enable a user to navigate to a pre-defined destination from a start point, a personal navigation device may have an internal system (such as a GPS receiver) for receiving location data, or may merely be connectable to a receiver which can receive location data. The personal navigation device may compute a route itself, or communicate with a remote server which is configured to compute the route and provides navigation information to the personal navigation device, or a hybrid device in which the personal navigation device itself and a remote server both play a role in the route computation process. These personal navigation devices are often mounted on or in the dashboard of a vehicle using a suction mount or other mounting means, and may thus readily be dismounted. Generally (but not necessarily), personal navigation devices are fully self-contained, such as including an internal GPS antenna, navigation software and map database, and can hence plot and display a route to be taken.
FIG. 1 is a functional block diagram illustrating a prior art personal navigation device 100. The personal navigation device 100 includes a receiver module 14, a memory 15, processor 16, a user interface 17, and a display module 18. The receiver module 14 is configured to receive a location signal, based on which the processor 16 may calculate the current coordinate of the personal navigation device 100. The processor 16 is configured to control the operation of the personal navigation device 100. A map database and a route-planning software are stored in the memory 15. After the user selects or inputs the information about a destination via the user interface 17, the processor 16 may execute the route-planning software so as to acquire all possible routes from the map database according to the current coordinate of the personal navigation device 100 and the coordinate of the destination. Among all possible routes, the best route may be displayed on the display module 18 for providing navigation instructions.
FIG. 2 is a diagram illustrating a prior art navigation method. The user may be navigated to a destination B from a start point A according to the suggested route provided by the personal navigation device 100 (represented by the arrow in FIG. 2). If the destination B does not provide parking facility, the user may need to park the vehicle in nearby parking lots C1-C3. If new to the neighborhood, the user may have trouble finding the right way to the destination B from the actual parking location. Uncertain about the final parking location, a new navigation instruction from the actual parking location to the destination B can only be acquired after the user actually finds an available parking lot. After parking the vehicle, the user needs to dismount the personal navigation device 100 and carry it at hand for consulting the new navigation instruction, and then re-mount the personal navigation device 100 to the vehicle on the way back, which causes inconveniences. If the user memorizes the new navigation instruction, the risk of getting lost still exists due to false memory. On the other hand, although thin regional maps are easy to carry, taking the trouble to get the regional maps of every unfamiliar region to be visited is not customary. A comprehensive atlas which contains detailed information of all possible destinations is too bulky to carry at hand, and is normally placed in the vehicle for reference.